This invention relates to ball break detection. It relates more particularly to apparatus for detecting the occurrence of a break in a hollow play ball when the ball is in play.
Certain racquet sports such as squash and tennis utilize a game ball having a flexible elastic wall defining a hollow interior which is filled with a compressible gas such as air to give the ball considerable resilience. When, during play, the ball is struck by a racquet or the ball strikes a hard surface, the wall of the ball is deflected inwardly thereby compressing the gas inside the ball so that the internal pressure rises dramatically. This increase in pressure gives the ball considerable potential energy so that the ball rebounds with appreciable velocity.
During the course of a game such sudden impacts can stress the ball to the extent that a break in the form of a hole, split or crack may develop in the wall of the ball. Accordingly when the ball next impacts the racquet or playing surface, the compression of the ball upon impact forces at least some of the fluid in the ball out through that opening thereby reducing the resilience of the ball to some extent. Resultantly, the next time the ball is hit by the racquet or next strikes the playing surface, it rebounds or behaves differently than it did prior to the break hereby making the ball harder to hit properly by the next player.
Oftentimes the damage to ball is progressive so that initially the crack or break in the wall of the ball is so small that it hardly affects the motion of the ball at all. However, at some point during the game, the break becomes sufficiently large as to change the overall resilience of the ball thereby giving the player who hit the ball last an unfair advantage over the other player or players. At some point, of course, the break becomes so noticeable to everyone that the ball is replaced. Before that point is reached, however, the ball may have been hit several times in its damaged condition giving an unfair advantage to one or another of the players, depending upon where the ball is struck by the racquet and where the ball is impacted by the playing surface.